1. Field
This application disclosure relates generally to I2C isolated, bidirectional communication systems, including isolated domain current source pull-ups, and features to detect data direction, maintain signal direction and detect an I2C acknowledge (ACK) signal.
2. Overview
Physical implementations of I2C bidirectional systems typically employ a bidirectional wired NOR bus using two wires to respectively communicate clock (SCL) and data (SDA) signals. The bus signal is commonly pulled up with a resistor or a current source and its value is defined by the system capacitance and maximum low voltage level (VOL) of a pull down device. Current I2C architectures can support one master or multiple master devices and from one to 127 slave devices. An ACK condition is a low input signal from a slave device on an SDA pin indicating the slave device has received a byte of data. The ACK signal may occur when the master device is in process of pulling down the signal and must be detected and communicated in an isolated system. Slave devices may incorporate clock stretching on the SCL pins. Clock stretching has a similar signature as an ACK signal, by pulling down and holding the clock signal initiated during the low portion of the clock phase.